Let's roll up our sleeves and solve this. We have 555 and we're going to multiply it by 156, essentially adding 555 to itself 156 times.
Step 1: 0 + 555 = 555
Step 2: 555 + 555 = 1110
Step 3: 1110 + 555 = 1665
Step 4: 1665 + 555 = 2220
Step 5: 2220 + 555 = 2775
Step 6: 2775 + 555 = 3330
Step 7: 3330 + 555 = 3885
Step 8: 3885 + 555 = 4440
Step 9: 4440 + 555 = 4995
Step 10: 4995 + 555 = 5550
Step 11: 5550 + 555 = 6105
Step 12: 6105 + 555 = 6660
Step 13: 6660 + 555 = 7215
Step 14: 7215 + 555 = 7770
Step 15: 7770 + 555 = 8325
Step 16: 8325 + 555 = 8880
Step 17: 8880 + 555 = 9435
Step 18: 9435 + 555 = 9990
Step 19: 9990 + 555 = 10545
Step 20: 10545 + 555 = 11100
Step 21: 11100 + 555 = 11655
Step 22: 11655 + 555 = 12210
Step 23: 12210 + 555 = 12765
Step 24: 12765 + 555 = 13320
Step 25: 13320 + 555 = 13875
Step 26: 13875 + 555 = 14430
Step 27: 14430 + 555 = 14985
Step 28: 14985 + 555 = 15540
Step 29: 15540 + 555 = 16095
Step 30: 16095 + 555 = 16650
Step 31: 16650 + 555 = 17205
Step 32: 17205 + 555 = 17760
Step 33: 17760 + 555 = 18315
Step 34: 18315 + 555 = 18870
Step 35: 18870 + 555 = 19425
Step 36: 19425 + 555 = 19980
Step 37: 19980 + 555 = 20535
Step 38: 20535 + 555 = 21090
Step 39: 21090 + 555 = 21645
Step 40: 21645 + 555 = 22200
Step 41: 22200 + 555 = 22755
Step 42: 22755 + 555 = 23310
Step 43: 23310 + 555 = 23865
Step 44: 23865 + 555 = 24420
Step 45: 24420 + 555 = 24975
Step 46: 24975 + 555 = 25530
Step 47: 25530 + 555 = 26085
Step 48: 26085 + 555 = 26640
Step 49: 26640 + 555 = 27195
Step 50: 27195 + 555 = 27750
Step 51: 27750 + 555 = 28305
Step 52: 28305 + 555 = 28860
Step 53: 28860 + 555 = 29415
Step 54: 29415 + 555 = 29970
Step 55: 29970 + 555 = 30525
Step 56: 30525 + 555 = 31080
Step 57: 31080 + 555 = 31635
Step 58: 31635 + 555 = 32190
Step 59: 32190 + 555 = 32745
Step 60: 32745 + 555 = 33300
Step 61: 33300 + 555 = 33855
Step 62: 33855 + 555 = 34410
Step 63: 34410 + 555 = 34965
Step 64: 34965 + 555 = 35520
Step 65: 35520 + 555 = 36075
Step 66: 36075 + 555 = 36630
Step 67: 36630 + 555 = 37185
Step 68: 37185 + 555 = 37740
Step 69: 37740 + 555 = 38295
Step 70: 38295 + 555 = 38850
Step 71: 38850 + 555 = 39405
Step 72: 39405 + 555 = 39960
Step 73: 39960 + 555 = 40515
Step 74: 40515 + 555 = 41070
Step 75: 41070 + 555 = 41625
Step 76: 41625 + 555 = 42180
Step 77: 42180 + 555 = 42735
Step 78: 42735 + 555 = 43290
Step 79: 43290 + 555 = 43845
Step 80: 43845 + 555 = 44400
Step 81: 44400 + 555 = 44955
Step 82: 44955 + 555 = 45510
Step 83: 45510 + 555 = 46065
Step 84: 46065 + 555 = 46620
Step 85: 46620 + 555 = 47175
Step 86: 47175 + 555 = 47730
Step 87: 47730 + 555 = 48285
Step 88: 48285 + 555 = 48840
Step 89: 48840 + 555 = 49395
Step 90: 49395 + 555 = 49950
Step 91: 49950 + 555 = 50505
Step 92: 50505 + 555 = 51060
Step 93: 51060 + 555 = 51615
Step 94: 51615 + 555 = 52170
Step 95: 52170 + 555 = 52725
Step 96: 52725 + 555 = 53280
Step 97: 53280 + 555 = 53835
Step 98: 53835 + 555 = 54390
Step 99: 54390 + 555 = 54945
Step 100: 54945 + 555 = 55500
Step 101: 55500 + 555 = 56055
Step 102: 56055 + 555 = 56610
Step 103: 56610 + 555 = 57165
Step 104: 57165 + 555 = 57720
Step 105: 57720 + 555 = 58275
Step 106: 58275 + 555 = 58830
Step 107: 58830 + 555 = 59385
Step 108: 59385 + 555 = 59940
Step 109: 59940 + 555 = 60495
Step 110: 60495 + 555 = 61050
Step 111: 61050 + 555 = 61605
Step 112: 61605 + 555 = 62160
Step 113: 62160 + 555 = 62715
Step 114: 62715 + 555 = 63270
Step 115: 63270 + 555 = 63825
Step 116: 63825 + 555 = 64380
Step 117: 64380 + 555 = 64935
Step 118: 64935 + 555 = 65490
Step 119: 65490 + 555 = 66045
Step 120: 66045 + 555 = 66600
Step 121: 66600 + 555 = 67155
Step 122: 67155 + 555 = 67710
Step 123: 67710 + 555 = 68265
Step 124: 68265 + 555 = 68820
Step 125: 68820 + 555 = 69375
Step 126: 69375 + 555 = 69930
Step 127: 69930 + 555 = 70485
Step 128: 70485 + 555 = 71040
Step 129: 71040 + 555 = 71595
Step 130: 71595 + 555 = 72150
Step 131: 72150 + 555 = 72705
Step 132: 72705 + 555 = 73260
Step 133: 73260 + 555 = 73815
Step 134: 73815 + 555 = 74370
Step 135: 74370 + 555 = 74925
Step 136: 74925 + 555 = 75480
Step 137: 75480 + 555 = 76035
Step 138: 76035 + 555 = 76590
Step 139: 76590 + 555 = 77145
Step 140: 77145 + 555 = 77700
Step 141: 77700 + 555 = 78255
Step 142: 78255 + 555 = 78810
Step 143: 78810 + 555 = 79365
Step 144: 79365 + 555 = 79920
Step 145: 79920 + 555 = 80475
Step 146: 80475 + 555 = 81030
Step 147: 81030 + 555 = 81585
Step 148: 81585 + 555 = 82140
Step 149: 82140 + 555 = 82695
Step 150: 82695 + 555 = 83250
Step 151: 83250 + 555 = 83805
Step 152: 83805 + 555 = 84360
Step 153: 84360 + 555 = 84915
Step 154: 84915 + 555 = 85470
Step 155: 85470 + 555 = 86025
Step 156: 86025 + 555 = 86580

So, 555*156 = 86580